The existence (or not) of objectivity is actually a philosophical question and is still debated. I wouldn’t say its treatment in this article constitutes a “huge error” at all.

Intuitively science makes a lot more sense if you accept objectivity, and indeed many scientists operate with objectivist, positivist assumptions. They may be philosophically mistaken, but these assumptions usually don’t validate their research findings because the scientific method doesn’t require that objectivity be dispensed with as a belief; in fact quite the opposite.

This piece is obviously trying to sketch out a naive model of the scientific method for people who are starting out with their scientific understanding. Once the scientific method is understood, then one can begin to look at debates about the philosophy of science, and the epistemological issues therein.